Selective Adsorption of Direct Group Anionic Dyes on Layered Double Hydroxide-Chitosan Composites

In this research, the potential of M2+/Al intercalated chitosan has been evaluated and good ability to reduce dyes in an aqueous solution. M2+/Al intercalated chitosan was prepared by anion exchange method and coprecipitation in a nitrogen atmosphere. Selectivity adsorption was studied to maintain the ability of M2+/Al intercalated chitosan for particle size of direct dyes (direct green, direct red, and direct yellow). To evaluate the adsorption process, M2+/Al intercalated chitosan was conducted with kinetic, isotherm, and thermodynamic parameters. The kinetic data fitted well by pseudo-second order and isotherm fitted Langmuir isotherm with qmax obtained 294.11 and 322.58 mg/g for Zn/Al-chitosan and Mg/Al-chitosan, respectively. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Modified Layered Double Hydroxide Mg/M3+ (M3+ = Al and Cr) Using Metal Oxide (Cu) as Adsorbent for Methyl Orange and Methyl Red Dyes

Mg/Cr-layered double hydroxide (Mg/Cr-LDH) and Mg/Al-layered double hydroxide (Mg/Al-LDH) intercalated metal oxide (Mg/Cr-Cu and Mg/Al-Cu) were synthesized by the co-precipitation method which is indicated by the X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Brunauer Emmett Teller (BET) analysis. Mg/Cr-LDH intercalated metal oxide increased its surface area from 21.5 to 38.9 m2/g, while the surface area of Mg/Al-LDH from 23.2 to 30.5 m2/g. The adsorption capacity of Mg/Cr-Cu is 64.156 mg/g for methyl orange (MO) and 78.740 mg/g for methyl red (MR), and the adsorption capacity of Mg/Al-Cu is 97.087 mg/g for MO and 108.696 mg/g for MR. Equilibrium time on the adsorption process occurred at 90 minutes with adsorption kinetics followed by pseudo-second-order (PSO). The adsorption isotherm followed the Langmuir isotherm equation. Data of thermodynamic parameters indicate that the adsorption process in this study occurs spontaneously and endothermically. The regeneration results show that Mg/Cr-Cu and Mg/Al-Cu can be used for the 5 cycles regeneration process of MO and MR adsorption process. Interactions that occur between adsorbents and adsorbate include physical interactions, interactions with the involvement of hydrogen bonds, and electrostatic interactions

Mg/Al-chitosan as a Selective Adsorbent in The Removal of Methylene Blue from Aqueous Solutions

The use of dyes in the textile industry is detrimental to aquatic biota and humans. Pollution caused by dye waste can be overcome by adsorption methods using adsorbents such as LDH. LDH is known as an adsorbent that is often found in the process of removing dye waste, but repeated use is not effective. This can be overcome by the LDH modification process using a supporting material such as chitosan. Modification of LDH can be done using coprecipitation or precipitation simultaneously at pH 10. XRD analysis where the peaks that appear in Mg/Al-chitosan are similar to the typical peaks of the constituent materials, namely Mg/Al and chitosan. This is confirmed by FTIR analysis where the spectrum that appears in Mg/Al-chitosan is similar to the spectrum in Mg/Al and chitosan. As well as BET analysis where there is an increase in the surface area of Mg/Al after being modified to Mg/Al-chitosan from 5.845 m2/g to 24.556 m2/g. In this study, the selectivity process for the dye mixture was carried out first with the most selective dye for the Mg/Al-chitosan adsorbent was methylene blue. Methylene blue was continued for adsorption processes such as isotherm adsorption kinetics and adsorption thermodynamics as well as adsorbent regeneration studies. The results showed that at 90 minutes the adsorption reached equilibrium. The adsorption capacity of Mg/Al increased after modification using chitosan from 84.746 mg/g to 108.696 mg/g. The adsorption process follows the Langmuir isotherm type where adsorption occurs chemically (monolayer). Regeneration studies show that Mg/Al-chitosan is an adsorbent that can be used repeatedly with stable adsorption effectiveness until the fifth cycle

High Selectivity and Stability Structure of Layered Double Hydroxide-Biochar for Removal Cd(II)

Composite M2+/Al-BC (Ca/Al-BC, Cu/Al-BC, and Ni/Al-BC) have been successfully synthesized. Composite and pristine materials were used as adsorbents of cadmium(II) [Cd(II)] in an aqueous solution. Firstly the performance of composite and pristine materials was evaluated by reusability properties until five cycles adsorption process followed with a determination of isotherms and adsorption thermodynamic properties. The results show composite has ten-fold surface area properties than starting materials. The adsorption capacities of CaAl-BC, CuAl-BC, and NiAl-BC at a temperature of 333 K were 156.250 mg/g, 149.254 mg/g, and 208.333 mg/g, respectively. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Layered Double Hydroxide/C (C=Humic Acid;Hydrochar) As Adsorbents of Cr(VI)

Layered double hydroxide (LDH) is known as a layered material that can be used as an adsorbent to remove pollutants from aqueous solutions. The use of layered double hydroxide as an adsorbent is not very effective due to its structure which is easily damaged so that it cannot be reused and its small surface area which results in a small adsorption capacity. This can be overcome by developing layered double hydroxide into a composite material. Modification of layered double hydroxide is done by using supporting materials in the form of humic acid and hydrochar. In this study the adsorbent was applied in the removal of Cr(VI) metal from aqueous solutions. The layered double hydroxide modification process was successfully carried out as seen from the XRD, FTIR, and BET analysis. XRD analysis shows the peaks that appear in Mg/Al-AH and Mg/Al-HC are peaks composed of their constituent materials, namely Mg/Al LDH, humic acid, and hydrochar. The vibrations that appear in Mg/Al-AH and Mg/Al-HC are vibrations originating from Mg/Al, humic acid, and hydrochar. The layered double hydroxide material composited with humic acid showed a surface area from 2.155 m2/g to 3.337 m2/g. The layered double hydroxide material composited with hydrochar showed a larger surface area than the Mg/Al LDH base material. The surface area increased 37 times, from 2.155 m2/g to 74.207 m2/g. The Mg/Al-AH composite showed the first adsorption ability of 89.064% and there was no significant decrease in the next cycle. The Mg/Al-HC composite showed adsorption ability in the first cycle which reached 97.079%, the ability to survive up to the fifth cycle with a final ability of 75.029%

Modification of Mg/Al-LDH Intercalated Metal Oxide (Mg/Al-Ni) to Improve The Performance of Methyl Orange and Methyl Red Dyes Adsorption Process

Modification of Mg/Al-LDH intercalated metal oxide (Mg/Al-Ni) was successfully formed by the coprecipitation method at pH 10, which is indicated by the XRD diffraction, FTIR spectrum, and BET analysis. Mg/Al-LDH increased surface area after intercalated Ni from 8.621 m2/g to 9.821 m2/g and improved performance in process regeneration which can be used in the three cycles. Mg/Al-LDH after intercalated metal oxide (Ni) increases adsorption capacity of is 69.930 mg/g to 71.429 mg/g for methyl orange (MO) and 77.519 mg/g to 98.039 mg/g for methyl red (MR). Equilibrium time on the adsorption process occurred at 90 minutes with adsorption kinetics followed pseudo-second-order (PSO). Thermodynamic parameters indicate that the adsorption process is spontaneous and endothermic with the physical adsorption process